The main error sources of ADC include comparator offset (Offset), capacitor mismatch (Mismatch), gain error (Gain error), etc., wherein the ADC capacitor mismatch caused by manufacture is impossible to avoid, causing non-linear change of the output characteristic curve of ADC, which influences the performance of ADC the most. Using a large capacitor unit is among the traditional simulation improvement methods, but it will consume the area and power. Or the linear characteristics of ADC are improved by substituting a small capacitor array for the large capacitor array, which, however, will increase the control difficulty and reduce the speed of ADC. Using the method of digital calibration of the adaptive filter algorithm is becoming a mainstream technology of calibrating capacitor mismatch. In an existing adaptive filter algorithm, generally comparing the output signal of ADC with another high-accuracy output signal of ADC to obtain an error value, correcting the weight according to the error value, and repeating the operation, thus finally making the output signal of ADC calibrated.